Synergistic sensitization of photographic systems with labile selenium and a noble metal



United States Patent Ofifice 3,297,446 Patented Jan. 10, 1967 man Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed July 1, 1965, Ser. No. 468,972 28 Claims. (Cl. 96107) This application is a continuation-in-part application of my copending application Serial No. 343,456 filed February 10, 1964, now abandoned.

This invention relates to photography and more particularly to noble metal sensitized photographic systems.

It is known that photographic systems such as silver halide systems, particularly gelatino silver halide emulsions, can be sensitized chemically with a combination of a noble metal sensitizer, e.g., a gold salt and a labile sulfur compound. Useful as such gold-sulfur sensitizer con1 binations are, there is a need in the art for photographic systems having greater speeds without concurrent increases a grain size, or reduced grain size for a given speed.

It is an object of this invention to provide novel noble metal sensitized photographic systems.

It is another object of this invention to provide novel noble metal sensitized photographic systems having improved speed and grain size relationships.

It is still another object'of this invention to provide photographic systems that can be sensitized with noble metals containing novel synergistic sensitizer combinations.

It is likewise an object of this invention to'provide silver halide photographic systems containing novel goldcontaining sensitizer combinations therefor.

Also, it is an object of this invention to provide gelatino silver halide emulsions sensitized with novel synergistic gold-containing sensitizer combinations therefor.

These and other objects of theinvention are accomplished with noble metal sensitized systems wherein vthe speed sensitivity of the system is increased with labile selenium. The noble metal moiety and the labile selenium moiety cooperate or synergize to impart substantially increased sensitivity to photographic systems that can be sensitized with noble metals. The noble metal moiety and the labile selenium moiety are more generally added to the emulsion as separate entities, although such is not necessary.

The selenium sensitizers useful in my invention include a Wide variety of labile selenium sensitizers, many having been previously suggested for use alone in sensitizing photographic silver halide emulsions. Suitable selenium addenda are disclosed in Sheppard et al. US. Patent 1,623,499, issued April 5, 1927, as well as Sheppard US. Patents 1,574,944, issued March 2, 1926, and 1,602,592, issued October 12, 1926. The labile selenium sensitizers of my invention which have been found to be particularly useful are organic selenium compounds wherein the selenium atom is doubly bonded to a carbon atom of the organic compound through a covalent linkage. Thus,

especially useful compounds include selenoamides, selenoketones (especially ketones having an alkyl radical attached to the moiety), selenocarboxylic acids and esters, etc. Useful groups of selenium sensitizers include aliphatic selenoureas wherein the aliphatic radical is, for example, an alkyl radical such as methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, etc. Such selenoureas have at least one hydrogen atom attached to the nitrogen atom thereof, thus making possible the formation of an enol tautomer. Also useful in my invention are analogous selenoureas containing one or more aromatic radicals, such as phenyl, tolyl, etc., or heterocyclic radicals, such as benzothiazolyl, pyridyl, etc., and aliphatic isoselenocyanates. It has also been found that colloidal selenium itself is a useful sensitizer, and this discovery was quite surprising in view of the disadvantageous effects of colloidal sulfur in silver halide emulsions.

Illustrative addenda suitable for furnishing the labile selenium moiety in the sensitizer combinations of the invention include:

colloidal selenium selenoacetone selenoacetophenone tetramethyleselenourea N- ,e-carboxyethyl) -N,N'-dimethylselenourea selenoacetamide diethylselenide 2-selenopropionic acid 3-selenobutyric acid methyl 3-selenobutyrate allyl isoselenocyanate dioctylselenourea The concentration of selenium sensitizer can be varied considerably depending upon the particular selenium addendum employed (some sensitizers being more efiicacious than others), the nature of the photographic system, the amount and chemical nature of the noble metal sensitizer, etc. In silver halide systems for example, I have found that useful results can be obtained using amounts as small as 0.05 mg. of selenium sensitizer per mole of silver halide although considerably larger amounts can also be employed, such as 5.0 mg. or more per mole of silver halide.

The term labile as used herein has the meaning well understood by those skilledfin the art of photography, i.e., a material which yields a silver selenide that is insoluble in water at room temperature (20C.) upon addition to an aqueous silver nitrate solution. For example, selenourea is a labile selenium compound, since silver selenide precipitates when selenourea is added to an aqueous silver nitrate solution. Similarly, colloidal selenium precipitates silver selenide upon addition to aqueous silver nitrate and is, therefore, a labile selenium addendum or sensitizer of invention.

The noble metale sensitizers useful in my invention include the Well known gold sensitizers which have been previously recognized as useful in the photographic art and found to be outstanding in their sensitizing action,

although other noble metal sensitizers can be used, including palladium, platinum, etc., sensitizers such as are disclosed in Smith et al. US. Patent 2,448,060, issued August 31, 1948. Typical suitable gold sensitizers are described in Waller et al. US. Patent 2,399,083, issued April 23, 1946, and Damschroder et al. US. Patent 2,642,- 361, issued June 16, 1953.

Illustrative addenda suitable for furnishing the noble metal moiety in the sensitizer combinations of the invention include:

gold chloride potassium aurate potassium auriaurite potassium auricyanide potassium aurithiocyanate gold sulfide gold selenide gold iodide potassium chloroaurate ethylenediamine-bis-gold chloride ammonium chloroplatinite, i.e. (NH PtCl ammonium chloropalladate, i.e. (NHQ PdCl and organic gold sensitizers having the formulas:

CH3 C I C-SAu C2 H5 Cl (III) (I? /O\ C\ /Cl N-CH o=orr-on=o 2 5 C-SAu N S (B2115 /S C\ /Cl la 2 5 CSAu N S 62115 l C-CHa 0 H; ADC];

(VI) S H: H:

C-C CCH=CH'N CHz C-C /N\ H: H: CH AuCh (VII) f /O gH; C 415 AuCh (VIII) S S The quantity of noble metal sensitizer useful in my invention can likewise be varied as in the case of selenium sensitizer. I have found, for example, that amounts varying from about 0.1 to 5.0 mg. of gold sensitizer per mole of silver halide are quite satisfactory.

It has been found that particularly useful results are obtained in my novel noble metal selenium sensitizing combinations in cases where a water-soluble thiocyanate compound is present. Typical thiocyanates include sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate, etc. Other water-soluble thiocyanates can be employed to equal advantage. The amount of thiocyanate compound used can likewise be varied, depending upon the particular system being sensitized, relative amounts of selenium and noble metal sensitizers, etc.

The sensitizing addenda used in my invention can be added in a variety of ways to photographic systems and at various stages in the preparation of such. In general, with respect to silver halide emulsions, such addenda can be added with useful effects at the completion of the Ostwald ripening and prior to one or more of the final digestion operations. The sensitizing addenda of the invention are preferably added to silver halide emulsions after the silver halide grains are substantially in their final size and shape. The addenda can be added in the form of their aqueous solutions, where they are soluble in water, or in an innocuous organic solvent where the sensitizer does not have sufficient solubility in water to be used in the form of an aqueous solution. Particularly useful organic solvents include ethanol, methanol, pyridine, acetone, dioxane, etc. That is, organic solvents which have a rather high degree of polarity are preferred. Where it is desired to add the sensitizing addenda in some other form than a solution, this procedure is also possible, especially where the sensitizer is available in the form of a colloidal suspension. In some cases, it is possible to add the present sensitizers suspended in an organic solvent which forms very small suspended particles in the photographic emulsion similar to the type of colloidal particle produced in preparing coupler dispersions. Dispersing media useful for this purpose include tricresyl phosphate, dibutyl phthalate, triphenyl phosphate, etc. Vacuum deposited photographic systems substantially free of conventional vehicles, binders or dispersing agents can also be sensitized in accordance with the invention. Such vacuum deposited photographic systems can be sensitized in accordance with the invention by incorporating the subject sensitizers in a coating or layer contiguous to the vacuum deposited light-sensitive material. Suitable vacuum deposited silver halide systems that can be sensitized in accordance with the invention are disclosed in Rasch et a1. application, U.S. Serial No. 415,596, filed December 3,

1964; Rees application, U.S. Serial No. 421,725, filed December 28, 1964; and Belgian Patent 639,020.

In the preparation of dispersions of light-sensitive materials such as silver halide and the like, useful in the invention, there can be employed as the dispersion agent gelatin or some other colloidal material, such as colloidal albumin, a cellulose derivative or a synthetic resin, for instance, a polyvinyl compound. Hydrophilic colloids which can be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe US. Patent 2,286,- 215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 19 to 26% as described in US. Patent 2,327,808 of Lowe and Clark, issued August 24, 1943; a water-soluble ethanolamine cellulose acetate as described in Yutzy, US. Patent 2,322,085, issued June 15, 1943; a polyacrylamide or an imidized polyacrylamide as described in Lowe, Minsk and Kenyon, US. Patent 2,541,474, issued February 13, 1951; copolymers (alone or in admixture with another colloid, e.g., gelatin) of an alkyl acrylate, e.g., ethyl or butyl acrylate, and acrylic acid, such as those described in Houck et al. US. Patent 3,062,674, issued November 6, 1962 and Houck et al. U.S. application Serial No. 139,313, filed September 19, 1961, now US. Patent No. 3,220,844; zein as described in Lowe U.S. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith US. Patent 2,768,- 154, issued October 23, 1956; or containing cyano-acetyl groups such as the vinyl alcohol-vinyl cyano-acetate copolymer as described in Unruh, Smith and Priest US. Patent 2,808,331, issued October 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in US. Patent 2,852,382 of Illingsworth, Dann and Gates, issued September 16, 1958. Mixtures of such dispersing agents in a wide range of proportions can be utilized, typical of such mixtures being mixtures of gelatin and an acrylate-acrylic acid copolymer.

I have found that the loss of density sometimes occurring when a gelatino photographic emulsion is dried can be prevented or substantially reduced by incorporating in the gelatin emulsions of my invention a water-soluble, gelatin-compatible vinyl monomer. Only a small amount of such an addendum is generally required, and frequently amounts as small as about 5%, based on total solids in the emulsion are useful, although it is obvious that much larger amounts, such as about 80%, can be employed in certain types of emulsions. Typical polymers which can be used'in combination with gelatin to prevent loss of density and thereby increase the covering power in the processed, dn'ed layer include the polyvinyl lactams, such as polyvinyl-pyrrolidone, as well as other polyvinyl lactams described in du Pont British Patent 867,899, published May 10, 1961. Other useful polymers include polyacrylamide types, such as polyacrylamide itself, or copolymers of acrylic amide with other ethylenically-unsaturated monomers, including acrylic acid, methacrylic acid, methacrylamide, acrylonitrile, methyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, or mixtures of these monomers. Other colloids useful in preventing or inhibiting such density losses include natural gums, salicyclic acid condensates, etc.

I have found that the speed of my noble metal-selenium sensitized emulsions can be further increased by including in the emulsions a variety of hydrophilic colloids, such as carboxymethyl protein of the type described in US. Patent 3,011,890, issued December 5, 1961. Polysaccharides of the type described in Canadian Patent 635,206 can also be used to further increase the speed of my emulsions.

Such emulsions can contain speed increasing compounds of the quaternary ammonium type of Carroll US. Patent 2,271,623, issued February 3, 1942; Carroll and Allen US. Patent 2,288,226, issued June 30, 1942; and Carroll and Spence US. Patent 2,334,864, issued November 23,

1943; or the polyethylene glycol type of Carroll and Beach US. Patent 2,708,162, issued May 10, 1955; or the quaternary ammonium salts and polyethylene glycols of Piper US. Patent 2,886,437, issued May 12, 1959; as well as the thiopolymers of Graham and Sagal US. Patent 3,046,129, issued July 24, 1962, and the Dann and Chechak US. Patent 3,046,134, issued July 24, 1962. Frequently, useful effects can be obtained by adding the aforementioned speed increasing compounds to the photographic developer solutions instead of, or in addition to, the photographic emulsions.

The photographic silver halide systems sensitized according to the novel technique of my invention are especially useful in the preparation of integral screen X-ray materials. Such X-ray materials have the advantage of convenience of handling and improved sharpness, inasmuch as they can be prepared using a single emulsion coated on but one side of the photographic support, as compared with conventional X-ray materials which have a silver halide emulsion layer coated on each side of the support (i.e., duplitized material). Since an opaque screen is employed in integral X-ray materials, the possibility of using an emulsion on only one side of the support is most desirable, and by using the novel emulsions of my invention, it is possible to use silver halide emulsions having finer grain to reach a given speed. This results in higher contrast for such a material, since finer grain emulsions inherently produce higher contrast. Thus, for the same grain size, it is possible to obtain higher speeds with the selenium-gold sensitized emulsions of my invention. An integral screen X-ray material using the novel emulsions of my invention can have the layer arrangement shown in French Patent 1,324,023, dlivr March 4, 1963. In such an arrangement the intensifying screen is located on the side opposite to the emulsion so that the screen remains with the positive after stripping. Other arrangements which can be used in the preparation of integral screen materials are described in Blake et al. US. Patent 2,887,379, issued May 19, 1959 (col. 8, lines 4 to 21). In a typical integral screen X-ray material of my invention, a conventional support is coated in succession with an intensifying screen, receiving layer, silver halide emulsion layer containing my novel combination of selenium and noble metal sensitizers, and if desired, a thin protective layer of gelatin (which can be omitted, if desired). Other arrangements will become apparent to those skilled in the art.

The chemical sensitizing addenda which I have described can be used in various kinds of photographic systems. In addition to being useful in X-ray and other nonoptically sensitized systems, they can also be used in orthochromatic, panchromatic, and infrared sensitive systems. The sensitizing addenda can be added to photographic systems before or after any sensitizing dyes which are used. Various silver salts can be used as the sensitive salt in silver halide systems such as silver bromide, silver iodide, silver chloride, or mixed silver halides, such as silver chlorobromide or silver bromoiodide. The present sensitizing agents can be used in emulsions intended for color photograph, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type, such as described in Godowsky US. Patent 2,698,794, issued January 4, 1955; in silver dye-bleach systems; and emulsions of the mixed-grain type, such as described in Carroll and Hanson US. Patent 2,592,243, issued April 8, 1952.

V I My synergistic sensitizing combinations can also be used in photographic systems intended for use in diifusion transfer processes which, for example, utilize undeveloped silver halide in non-irnage areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott US. Patent 2,352,014, issued June 20, 1944, and Land U.S. Patents 2,584,029, issued January 29, 1952; 2,698,236, issued December 28, 1954; 2,543,181, issued February 27, 1951 and 2,698,245, issued December 28, 1954; and Yackel et al. U.S. Patent 3,020; 155, issued February 6, 1962. My photographic systems can be advantageously used in diffusion transfer systems utilized for document copying, and in those wherein a silver halide emulsion layer is coated adjacent to a fogged silver halide emulsion layer or a layer containing silver precipitating nuclei, such as nickel sulfide. The sensitive emulsion, following development, is then washed off, leaving the positive image .in the light-insensitive layer containing the diffused silver image.

The present photographic systems can also be used in color transfer processes which utilize the diffusion transfer of an image-wise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land U.S. Patents 2,559,643, issued July 10, 1951 and 2,698,798, issued January 4, 1955; Land and Rogers Belgian Patents 554,933 and 554,934, granted August 12, 1957; International Polaroid Belgian Patents 554,212, granted July 16, 1957 and 554,935, granted August 12, 1957; Yutzy U.S. Patent 2,756,142, granted July 24, 1956 and Whitmore and Mader Canadian Patent 602,607, issued August 30, 1960. The sensitizing combinations are compatible with a wide variety of dye-developer combinations, including anthraquinone dye developers, such as 4-[1',5-bis-(2,5"- dihydroxyphenyl) 3 pentyl] amino-1-hydroxyanthraquinone, or azo dye developers, such as 2,4-bis-(2',5'-dimethoxy 3-[2"-(2",5-dihydroxy-4'"-methylbenzoyl) isopropyl]p'henylaso)-1-naphthol. Such dye developers can be incorporated in the light-sensitive emulsions themselves, or they can be incorporated in a hydrophilic colloid (e.g., gelatin) layer located contiguous to the noble metalselenium sensitized light-sensitive emulsion.

Photographic emulsions sensitized by the novel means described herein can be used in the preparation of photographic products wherein a photographic developing agent is incorporated in the emulsion itself, or in a hydrophilic colloid layer contiguous with the emulsion, for example, in photographic products of the type described in Yutzy et al. U.S. Patent 2,725,298, issued November 29, 1955, or in Yutzy et al. U.S. Patent 2,739,890, issued March 27, 1956. The novel photographic systems of my invention can be used in the production of photographic products containing, for example, at least about 5 grams per mole of silver halide of a developing agent, such as 1-phenyl-3- pyrazolidone and wherein the emulsion is coated on a fibrous support which contains sufiicient moisture so that upon heating the exposed element, a negative silver image is obtained directly without the application of liquids. Such a product is described in Stewart et al. U.S. Application Serial No. 221,031, filed September 4, 1962. This is not to say that the emulsions of my invention cannot be used in liquid systems which may or may not use a wide variety of processing solutions or viscous liquids, including systems which use pod processing. They can also 'be used in the preparation of photographic materials which are designed to be processed in non-aqueous systems or in systems designed to be processed by the application of steam.

The novel photographic systems of the invention can also be used in monobath processes such as are described in Haist et al. U.S. Patent 2,875,048, issued February 24, 1959, and in web-type processes, such as the one described in Tregillus et al. U.S. Patent Application Serial No. 835,473, filed August 24, 1959.

Also, the novel photographic systems of the invention can be used in the preparation of lithographic printing plates using, for example, techniques as described in Kodak French Patent 1,280,832, dlivr November 27, 1961.

As with many high-speed photographic systems, particularly sliver halide systems, chemical fog can sometimes be a problem. It has been found that the photographic systems of my invention can be usefully stabilized by certain stabilizers or antifoggants. Useful stabilizing compounds for the emulsions of my invention include the salts of noble metals, especially palladium and platinum, including such salts as are described in Trivelli and Smith U.S. Patents 2,566,245, issued August 28, 1951 and 2,566,- 263, issued August 28, 1951. Another group of stabilizers which are quite useful in my invention comprise the alkane, areneand heterocyclic sulfinic acids and their water-soluble salts (sodium benzene sulfinate, sodium anthraquinone sulfonates, ethane disulfinic acid, etc., including stabilizers disclosed in Brunken U.S. Patent 2,057,764, issued October 20, 1936). Another group of useful stabilizing compounds include urazole stabilizers, such as urazole, 4- phenyl urazole, l-ethyl dithiourazole, etc., including stabilizers disclosed in Howe U.S. Patent 2,538,599, issued December 19, 1950. It has also been found that the photographic systems of the invention can be effectively stabilized with disulfide compounds, including the cyclic disulfides of Kodak Belgian Patent 569,317, or the aliphatic disulfides of Herz and Kalenda U.S. Patent 3,043,- 696, issued July 10, 1962. Another group of disulfide stabilizing compounds which have useful effects in my invention include those containing a carbamylalkyl radical, wherein the carbamyl radical is aliphatic or cycloaliphatic (e.g., where the nitrogen atom of the carbamyl radical forms a part of a teterocyclic ring, such as piperidyl, morpholinyl, etc., as in the case of bis-(N-morpholinylcarbonyloxyethyl)-disulfide). Also useful in stabilizing the emulsions of my invention is Nitron and Similarly constituted tetrazoles, particularly Nitron in combination with a calicylic acid such as 5-(1,1,3,3-tetramethylbutyl)- salicyclic acid. 1-phenyl-5 mercaptotetrazoles are useful stabilizers in the invention. Water-soluble salts of Group II elements of the Periodic Table such as magnesium, calcium, strontium, barium, cadmium and zinc, organic tertiary phosphines and azaindenes such as triazindenes, tetrazaindenes and pentazaindenes are also useful stabilizers in the photographic systems of the invention. Typical suitable azaindenes are disclosed in Heimbach and Kelly U.S. Patents 2,444,605 and 2,444,606, issued July 6, 1948; Heimbach U.S. Patents 2,444,607, issued July 6, 1948, and 2,450,397, issued September 28, 1948; Heimbach and Clark U.S. Patent 2,444,609, issued July 6, 1948; Allen and Reynolds U.S. Patents 2,713,541, issued July 19, 1955, and 2,743,181, issued April 24, 1956; Carroll and Beach U.S. Patent 2,716,062, issued August 23, 1955; Allen and Beilfuss U.S. Patent 2,735,769, issued February 21, 1956; Reynolds and Sagal U.S. Patent 2,756,- 147, issued July 24, 1956; Allen and Sagura U.S. Patent 2,772,164, issued November 27, 1956, and Z. Wiss. Phot., vol. 47, 1952, pages 2 to 28.

A particularly useful class of stabilizers or antifoggants that can be utilized to control fog in the photographic systems of the invention are the derivatives of hydroxy carboxylic acids described in the copending application of Hum-phlett, U.S. Serial No. 413,962, filed November 25, 1964, and which stabilizer addenda can be represented by the following Formulas A and B,

'l- ($11M b H (emu l;

and

(tiuaz)n wherein: M and Z are each hydroxy radicals or acyloxy radicals ll C R wherein R is an alkyl radical or an aryl radical) X is a hydrogen atom, an acyloxymethyl radical I (-CHgO (J) R2 wherein R2 is an alkyl radical or an aryl radical) or a carbinol radical (CH OH); Y is a carboxy radical a carbamyl radical I! (CNH2) or a radical having the formula wherein R is an alkyl radical (more generally having 1 to 2 carbons, particularly when Z is a hydroxyl radical); A is a carbinol radical, a radical having the formula as described for Y, a carboxy radical, an acyloxymethyl radical or a carbamyl radical; m is an integer of 2 to 3; n is an integer of 1 to 5; and o is an integer of 0 to 2. The subject addenda contain at least one carbamyl or ester moiety including 7 or 6 lactone or inner ester groups (e.g., Formula A) as well as the more conventional ester groups described above II (as, o R, 0 OR Hence, at least one of A, Y and Z of Formula B forms a carbamyl or an ester radical. Typical useful antifoggant addenda can be represented by the following more subgeneric formulas:

wherein: R is an alkyl radical having 1 to 2 carbon atoms; R and R are each an alkyl radical which more generally has 1 to 8 carbon atoms or a phenyl radical, including substituted phenyl radicals; R is an alkyl radical which more generally "has 1 to 8 carbon atoms or a hydrogen atom; p is an integer of 2 to 3; and q is an integer of 1 to 5. Other subgeneric formulas defining antifoggant addenda of the invention included Within generic Formulas A and B can :be formulated. The alkyl substituents described above suitably have 1 to 20 carbon atoms, and preferably 1 to 8 carbon atoms, including methyl, ethyl, isopropyl, butyl, heptyl, octyl, decyl, octadecyl, eicosyl and the like. The aryl substituents described above include such radicals as phenyl, tolyl, naphthyl and the like, phenyl being preferred.

The above-described stabilizers or antifoggants can be utilized in conventional antifoggant amounts, the amount utilized varying with the particular stabilizer and the effect desired in accordance with usual practice. Mixtures or combinations of more than one of the abovedescribed stabilizers can be utilized. Such stabilizers, e.g., the azaindenes, which are normally added just prior to coating may, if desired, be included during the chemical sensitization of the silver halide emulsion.

The novel sensitizer combinations of a noble metal and a labile selenium described herein can be utilized to sensitize any photographic system that can be sensitized with noble metals. The invention thus has utility, not only for silver halide photographic systems, but also, for other light-sensitive systems such as other light-sensitive silver salts, thallous halides, cuprous halides, lead halides and related light-sensitive heavy metal salts.

The following examples will serve to illustrate the useful effects obtained in my invention when a combination of noble metal gold sensitizer and selenium sensitizer is employed.

EXAMPLE 1 A coarse-grained, gelatino silver bromoiodide emulsion containing about 6 mole percent iodide was chemically sensitized by adding 2 mg. per mole of silver halide of sodium thiosulfate (a labile sulfur compound), 20 mg. per mole of silver halide of potassium thiocyanate and 0.75 mg. per mole of silver halide of the gold salt, potassium chloroaurate. These addenda were intimately incorporated in the emulsion after ripening but prior to digestion. The emulsion was then heated for 15 minutes at 60 C. A second portion of the same unsensitized emulsion was chemically sensitized exactly as described, except that the sodium thiosulfate was replaced with 0.2 mg. per mole of silver halide of N,N-dimethylsele-nourea (a labile selenium compound). After sensitization, the emulsion was heated for about 24 minutes at 60 C. Each batch of chemically sensitized emulsion was separately coated'on conventional cellulose acetate film support and then dried. The dried coatings were then exposed to daylight quality illumination on an Eastman Ib sensitometer and developed for 5 minutes in a developer having the following composition:

Water, about 125 F.-(50 C.) cc 500.0 N-methyl-p-aminophenol sulfate grams 2.5 .Sodium sulfite, desiccated d0 30.0 Hydroquinone do 2.5 Sodium metaborate "do"-.. 10.0 Potassium bromide do 0.5

Water to make 1.0 liter.

The developed emulsion was then fixed in the usual manner with thiosulfate, washed with water and dried. The following results were obtained:

TABLE I Type of sensitizing Relative -y Fog Speed Sulfur-gold l. 02 0. O7 Selemum-gold 141 0. 86 O. 11

EXAMPLE 2 11 larly finished by heating for a few minutes at 60 C. Each batch of emulsion was then separately coated on a cellulose acetate film support, dried and exposed, developed, fixed, washed and dried as described in Example 1. The following results were obtained.

TABLE II Type of sensitizing Relative 7 Fog Speed Sulfur-gold 100 1. 27 0. 06 Selenium-gold 141 1. 17 0. 11

This example shows that my invention operates in emulsions containing no thiocyanate salt, although such salts do have particularly useful effects.

EXAMPLE 3 A coarse-grained, gelatino silver bromoiodide emulsion of the type used in medical radiography, or conventional high speed negative photography, was chemically sensitized with compounds identified in Table III and at the concentrations (mg/silver mole) shown in Table HI. Each portion of sensitized emulsion contain 40 mg. of potassium thiocyanate per mole of silver halide, and each was separately coated on conventional cellulose acetate film support and dried. The dried coatings were then separately exposed to daylight quality illumination on an Eastman lb sensitometer and developed in a conventional hydroquinone-Elon (N-methyl-p-aminophenol sulfate) developing composition, such as described in Example 1. The developed coatings were then fixed, washed and dried in the usual manner. The following sensitometric data were obtained:

TABLE III Coating Addenda Rel. Gamma Fog N0. Speed Sulfur (2.0) plus gold (.75) 100 0.85 09 Selenium-1 (0.2) plus gold (.75) 159 0.71 16 Selenium-2 (0.20) plus gold (.75)- 166 0.89 .10 Sulfur (2.0) plus gold (.75) 100 0. 71 .06 Selenium-1 (0.25) plus gold (125)-- 159 o. 64 09 Selenium-2 (0.25) plus gold (1.25)-- 148 0. 68 12 Sulfur (4.0) plus gold (.53) 100 1. 98 10 Selenium-1 25) plus gold (.7) 195 1. 40 11 204 1. s1 1s Sulfur (2.0) plus gold 100 0. 93 G Selenium-1 (.2) plus gold (.75) 151 1. 12 09 Selenium4i (-3) plus gold (.75) 141 1. 07 12 Sulfur (2.0) plus gold (.75) 100 0.81 SeleniumA (.25) plus gold (.75) 166 0. 76 12 In Table III:

Sulfur means sodium thiosulfate Gold means potassium chloroaurate Selenium-1 means dimethylselenourea Selenium-2 means colloidal selenium Selenium-3 means diethylselenourea Selenium-4 means selenourea Example 4 below illustrates the use of my novel sensitizing combinations in a photographic silver halide emulsion designed especially for use in a lithographic process. An emulsion suitable for this purpose can be prepared as described in U.S. Patent 2,756,148.

EXAMPLE 4 A fine grain high contrast gelatino silver chlorobromide emulsion containing 90 mole percent chloride was chemically sensitized by adding, per mole of silver halide, 1.78 mg. of sodium thiosulfate and 1.72 mg. of potassium chloroaurate and heating for 12 minutes at 65 C. A second portion of this emulsion was chemically sensitized TABLE IV Coating No. Type of Sensitizer Relative 7 Fog Speed :1 Sulfur-Gold 100 13. 0 01 b Selenium-Gold 191 13.0 01

The developer has the following composition:

Avoirdupois Metn'e Water, about 90 F. C.) 64 ounces 2.0 liters. Sodium sultlte, desiccated 4 more 120.0 grams. Paraforrnaldehyde 1 oun 30.0 grams. Potassium metabisulfite 150 grains 10.5 grams. Boric acid, crystal 1 ounce 30.0 grams. Hydroquinone 3 ounces 90.0 grams. Potassium bromide 90 grains 6.3 grams. Water to make 1 gallon. 4.0 liters.

EXAMPLE 5 In a manner similar to that described in Table G, Column 25 of U.S. Patent 3,046,129, issued July 24, 1962, a conventional photographic gelatino silver bromoiodide emulsion was divided into three aliquot portions, each portion contaning a conventional magenta coupler, such as one of those identified in Fierke et a1. U.S. Patent 2,801,171 (e.g., coupler N0. 7). Sample (a) contained in addition to the coupler dispersion, a sulfur sensitizer, such as sodium thiosulfate at 2 mg. per mole of silver halide and a gold sensitizer, such as potassium chloroaurate at 0.75 mg. per mole of silver halide. A second aliquot portion (b) was sensitized with the same gold chloride salt and with dimethylselenourea at 0.2 mg. per mole of silver halide. Aliquot sample (c) was sensitized to its optimum sensitivity with aurous thiosulfate at 3.3 mg. per mole of silver halide and dimethylselenourea at 0.2 mg. per mole of silver halide. Each of the coatings contained the tetrazole stabilizing compound, 5-(4-cyanophenyl)tetrazole monohydrate, at a concentration of about 5 grams per mole of silver halide. The three samples of emulsions were coated on separate cellulose acetate film supports and dried. The film samples were then exposed to daylight quality illumination in an Eastman type Ib sensitometer and given a conventional negative development in a hydroquinone, N-methyl-p-aminophenol sulfate developer as described in Example 1. The coatings were then flashed to white light and developed once again in an alkaline color developing composition containing 4-amino- N,N-diethyl-3-methylaniline hydrochloride as the active developing agent. The metallic silver was then removed by successive treatments with a ferricyanide bleach bath and fixing bath, followed by conventional water washing. The following results were obtained:

TABLE V Magenta Reversal Sample No.

Relative Shoulder Dmx Speed EXAMPLE 6 A fine-grained, green-sensitive photographic gelatino silver bromoiodide emulsion was prepared as'described in US. Patent 3,046,129 and separate portions Were sensitized With either a gold salt and a sulfur sensitizer (sample a in Table VI) or a gold salt and a selenium sensitizer (sample 12 in Table VI) as described in Example 1. The coatings were then processed as described in Example 5, using a magenta-forming developer of the type described in Example 2 of US. Patent 2,950,970. The following results were obtained:

TABLE VI Magenta Reversal Sample No.

Relative Shoulder Dmn x Speed Typical color-forming compounds or couplers which are useful in color photography, according to our invention, include the following:

Couplers producing cyan images 5- (p-amylphenoxybenzenesulfonamino -l -naphthol 5- (N-benzyl-N-naphthalenesulfonamino) 1 -naphthol 5-(n-benzyl-N-n-valerylamino) -1-naphthol 5 -caproylamino-1 -n aphth ol Z-chloro -5 (N-n-valeryl-N-p-isopro pylb enzyl amino) -1- naphthol V 2,4-dichloro-5 p-nitrobenzoyl-;3-o'hydroxyethyl-arnino l-naphthol 2,4-dichloro-5-palmitylamino-1 -naphthol 2,2'-dihydroxy-5 ,5 -dibromostilbene S-diphenylethersulfonamido-1-naphthol l-hydroxy-Z- (N-isoamyl-N-phenyl naphthamide l-hydrxy-2- (N-p-sec. amylphenyl naphthamide 8-hydroxyl -a-naphthoyl- 1 ,2,3 ,4-tetrahydroquinoline 2-1 auryl-4-chlorophenol l-naphthol-2-carboxylic-anaphthalide 1-n aphthol-S-sulfo-cyclohexylarnide 5-phenoxyacetamino-1-naphthol 5-5-phenylpropionylaminol-nap hthol Monochl or-S- (N y-phenylp ropyl-N-p-sec.-amylbenzoylamino) -1-naphthol Z-acetylamino-S -methylphenol 2-benzoylamino-3 ,5 -dimethylphenol Z-a (p-tert. amylphenoxy) n-butyrylamino-S-methylphenol 6-{7-{4-[7-(2A-di-t81t. amylphenoxy) butyramido] phenoxy} acetamido}-2,4-dichl ore-3 -methylphenol 1-hydroxy-2-[5-(2,4'di-tert. amylphenoxy) -n-butyl] naphthamide 2-0: (p-tert. amylphenoxy) -n-butyrylamino-4-chlor0-5- methylphenol 2- (p'-tert. amylphenoxy-p-benzoyl) amino-4-chloro-5- methylphenol 2-(4"-tert. amyl-3'-phenoxybenzoylamino) -3 ,5 -dimethyll-phenol 2-phenylacetylamino-4-chloro-5 -methyl phenol 1 4 2-benzoylamino-4-chloro-5-rnethylphenol 2-anilinoacetylamino-4-chloro-5 -methylphenol 2-{4- [a- (4"-tert. amylphenoxy) -n-butyrylamino] benzoylamino}-4-chloro-5-methylphenol 2- [4,3"- (4"'-tert. amylphenoxy) benzoylamino] benzoylamino-4-chloro-5-methylphenol 2-p-nitrobenzoylamino-4-chloro-5-methylphenol Z-m-aminobenzoyl-4-chloro-5-methylphenol Z-acetamino-4-chloro-5-methylphenol 2. 4'-sec. amylbenzamino -4'chlo-ro-5-methylphenol 2 (4'-n-amyloxybenzamino) -4-chlor0-5-methylphenol 2 (4'-phenoxybenzoylamino phenol 2(4"-tert. amyl-3 '-phenoxybenzoylamino phenol 2- a- 4'-tert. butylphenoxy) propionylamino] phenol 2- a- (4-tert. amyl) phenoxypropionylaminol phenol 2-[N-methyl-N-(4"-tert. amyl-3'-phenoxybenzoylamino) phenol 2- (4"-tert. amyl-3 '-phenoxybenzoylamino) -3 -methyll-phenol 2-(4"-tert. amyl-3' phenoxybenzoylamino) -6-methyll-phenol 2- (4"-tert. amyl-3 '-phenoxybeuzoylamino) -3 ,6-dimethylphenol 2,6-di (4"-tert. amyl-3 '-phenoxybenzoylamino) -1-pheno1 Z-a- 4'-tert. amylphenoxy) butyrylamino- 1 -phenol 2 (4"-tert. amyl-3'-phenoxybenzoylamino -3,5-dimethyl-1-phenol 2- [a- (4-tert. amylphenoxy) -n-butyrylamino -5-methyll-phenol 2 (4"-tert. amyl-3 '-phenoxybenzoylamino) -4-ch1orol-phenol 3- a- (4'-tert, amylphenoxy) -n-butyrylamino] -6-chlorophenol 3 4"-tert. arnyl-3'-phenoxybenzoylamino )phenol 2- [a-( 4'-tert. amylphenoxy) -n-butyrylamino] -6-chlorophenol '3 a- (4'-tert. amylphenoxy -n-,butyrylamino] -4-chlo-rophenol 3 oz- 4'-tert. amylphenoxy) -n-butyrylamino] -5-chlorophenol 3 oz- 4'-tert. amylphenoxy) -n-butyrylamino] -2-chlorophenol 2-a-(4'4Z61t. amylphenoxybutyrylamino) -5-chlorophenol 2- (4"-tert. amyl-3 '-phenoxybenzoylamino) -3 -chlorophenol S-benzene sulfoaminol-naphthol 2,4-dichloro-S-benzenesulfonarnino-1-naphthol 2,4-dichloro-5-(p-toluenesulfonamino) -l-naphtho1 5-( 1,2,3 ,4-tetrahydronaphtha1ene-6=sulfamino) -1- naphthol 2,4-dichloro-5-(4'-bromodiphenyl-4-sulfonamino) -1- naphthol 5-(quinoline-5sulfamino)-1-naphtho+l Any of the acylaminophenol couplers disclosed in Salminen and Weissberger US. Patent 2,423,730, dated July 8, 1947, can be used as couplers for the cyan image,

I CH3 czHs Couplers producing magenta images l-p-sec. amylphenyl-3-n-amyl-5-pyrazolone 2-cyanoacetyl-5- (p.-sec. amylbenzoylarnino) coumarone Z-cyanoacetylcoumarone-S-(n-amyl-p-sec. amylsulfanilide) 2-cyanoacetylcoumarone-5- (N-n-amyl-p -tert. amylsulfanilide) Z-cyanoacetylcoumarone -5-sulfone-N-n-butylanilide Z-cyanoacetyl-S-benzoylamino-coumarone Z-cyanoacetylcoumarone-S-sulfondimethylamide 2-cyanoacetylcoumarone-5-sulfon-N-methylanilide Z-cyanoacetylnaphthalene sulfon-N-methylanilide 2-cyanoacetylcoumarone-S- (N-y-phenylpropyl) -ptert. amylsulfonanilide 1-p-laurylphenyl-3 -methyl-5-pyrazolone l-li-n aphthyl-3 -amyl-5 -p yrazol one 1-p-nitrophenyl-3-n-amyl-5-pyrazolone 1-p-phenoxyphenyl-3 -n-amyl-5-pyrazolone 1-phenyl-3 -n-amyl-5-pyrazolone 1,4-phenylene bis-3 1-phenyl-5-pyrazolone) 1-phenyl-3 -acetylamino-S-pyrazolone 1-phenyl-3 -propionylamino-S-pyrazolone 1-phenyl-3 -n-valerylamino-5-pyrazolone 1-phenyl-3 -cl1loro acetylamino-S-pyrazolone 1-phenyl-3-dichloroacetylamino-S-pyrazolone 1-phenyl-3 -benzoylamino-S-pyrazolone 1-phenyl-3 (m-aminobenzoyl) amino-S-pyrazolone 1-phenyl-3- (p-sec. amylbenzoylamino -5-pyrazolone 1-phenyl-3 -diarnylbenzoylamino-S-pyrazolone 1-phenyl-3 -fl-naphthoylamino-S-pyrazolone 1-phenyl-3-phenylcarbarnylamino-S-pyrazolone 1-phenyl-3 -palmitylamino-S-pyrazolone 1-pheny1-3 -benzenesulfonylamino-S-pyrazolone 1- (p-phenoxyphenyl) -3-(p tert. amyloxybenzoyl amino- S-pyrazolone 1-(2',4',6-tribromophenyl -3-benzamido-5-pyrazolone 1-(2',4,6-trichlorophenyl -3 -benzamido-5-pyrazolone 1 (2',4',6-trichlorophenyl) -3 -phenylacetamido-5- pyrazolone 1-(2',4',6'-tribromophenyl) -3 -phenylacetamido-5- pyrazolone 1-(2',4-dichlorophenyl)-3-[3"-(2',4'-di-tert. amylphenoxyacetamido benzamido} -5-pyrazolone 1- 2',4',6'-trichlorophenyl -3- [3 2',4"'-di-tert. amylphenoxy-acetamide)benzamido]-5-pyrazolone 1- (2',4',6-tribromophenyl -3- 3"-( 2,4"'-di-tert. amylphenoxy-acetamido)benzamido1-5-pyrazolone 1- (2',4',6'-trichlorophenyl -3- [5- 2',4"'-di-te-rt. amy1- phenoxy) -propion amido] -5-pyrazolone 1-( 2',4',6-tribromophenyl) -3 [p- 2",4"-di-tert. amylphenoxy -propi0namido] -5-pyrazolone 1- 2,5'-dichloro) -3 3 (4"-tert. amylphenoxy) benzamido] -5-pyrazolone 1-( 2',4',6'-tribromophenyl -3- [3"- (4"-tert. amylphenoxy) benzamido] -5-py-razolone 1-(2',5-dichlorophenyl -3- [3 (2',4"'-di-tert. amylqahenoxyacetamido) benzamido] -5-pyrazolone Couplers producing yellow images N-amyl-p-benzoylacetaminobenzenesulfonate N- (4-anisoylacetaminobenzenesulfonyl -N-benzyl-mtoluidine N- 4-benzoylacetaminobenzenesulfonyl) -N-benzy1-mtoluidine N- 4-benzoylacetaminobenzenesulfonyl) -N-n-amyl-ptoluidine N- 4-benzoyl acetaminobenzenesulfonyl) -N-benzylaniline w- (p -Benzoylbenzoyl) acetanilide w-B enzoylacet-Z,S-dichloroanilide When my invention is employed to increase the speed of photographic emulsions intended for use in color photography in systems wherein a dye e.g., dye-bleach process) or the color-forming components are incorporated in the emulsions themselves, it is to be understood that these bleachable dyes or color-forming components can be incorporated in the emulsions according to any of the methods well known to those skilled in the art of photography. Since it is desired that the color-forming components or couplers not wander from the layers in which they are incorporated, couplers which do have wandering tendencies can be employed in a useful manner according to the technique described in Jelley and Vittum US. Patent 2,322,027, issued June 15, 1943. This method comprises adding the color couplier to a water-immiscible crystalloidal solvent, such as tricresyl phosphate or dibutyl phthalate and adding the solution to an aqueous emulsion. Where the couplers are characterized by inherent non-wandering characteristics due to the presence in the coupler molecules of a fatty type radical e.g., 1-(2,4,6 trichlorophenyl)-3-n-pentadecyl-S-pyrazolone; l-phenyl-3-n-pentadecyl-4-(1-phenyl-5-tetrazolylthio) 5- pyrazol one; 1-phe11y1-3-( 3,5 d sulfobelnz'amido -4-( 2-hydroxy-4-n-pentadencylphenylazo) S-pyrazolone dipotassium salt, etc.), the coupler can be incorporated in the emulsion simply by dissolving it in a convenient organic solvent which does not have any deleterious effect upon the emulsion. Of course, the nature of the solvent will vary depending upon the solubility characteristics of the particular coupler. In general, solvents, such as pyridine, triethanolamine, ethyl alcohol, etc., can be employed for this purpose.

When used in the preparation of photographic systems such as silver halide systems intended for color photography such systems can be optically sensitized with cyanine and rnerocyanine dyes, such as those described in Brooker US. Patents 1,846,301, issued February 23, 1932, 1,846,302, issued February 23, 1932, and 1,942,854, issued January 9, 1934; White US. Patent 1,990,507, issued February 12, 1935; Brooker and White US. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939, 2,493,747, issued January 10, 1950, and 2,739,964, issued March 27, 1956; Brooker and Keyes US. Patent 2,493,748, issued January 10, 1950; Sprague US. Patents 2,503,776, issued April 11, 1950 and 2,519,001, issued August 15, 1950; Heseltine and Brooker US. Patent 2,666,761, issued January 19, 1954; Heseltine US. Patent 2,734,900, issued February 14, 1956; VanLare US. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

EXAMPLE 7 A coarse-grained silver bromoiodide emulsion of the type described in Example 1 above was divided into several aliquot portions and each portion was then chemically sensitized as described below. The emulsions were then coated on separate supports and processed as described in Example 1 above. The following results were obtained:

TABLE VII Coat- Relaing Addenda (mg/Ag mole) tive Gamma Fog No. Speed A Sodium thlosuliate (2.2) 100 .79 06 B N,N-Dimetl1ylselenourea (.5) 94 .67 .08 C Sodium thiosulfate (2.2) plus potassium chloroaurate (.75) 224 94 11 D N,NDimethylselenourea (.25) plus I potassium chloroaurate (.75) i 331 .74 10 My invention advantageously uses selenium compounds or metallic selenium, and with respect to the selenium compounds useful in my invention, it is important to note that these compounds must contain at least one labile selenium atom, determined as described above. Example 8 illustrates that compounds containing a selenium atom which is not labile, do not provide the useful effects described above.

EXAMPLE 8 An emulsion of the type described in Example 7 above was coated and processed as described in Example 1. Aliquot portions of the emulsion were treated with sensitizer addenda before coating, these addenda being identified in the following table in mg. per mole of silver halide.

As indicated above, it has been found that the seleniumgold sensitized emulsions of my invention can be further improved in speed by adding to the emulsion a conventional polyethylene glycol sensitizer, alone or in combination with an onium salt of the type described in U.S. Patents 2,400,532; 2,423,549; 2,441,389; 2,944,898; 2,944,900; or 3,062,645. Quaternary ammonium salts of the type described in U.S. Patent 3,017,271 can also be used. This effect is illustrated in the following example.

EXAMPLE 9 A selenium-gold sensitized, gelantino silver bromoiodide emulsion was prepared and coated as described in Example 1 above. A separate portion of the same emulsion was prepared and then modified by the addition of 0.66 g. of a olyethylene glycol sensitizer (referred to in Table IX as PEG) having an average molecular weight of 1500 and 0.4 g. per mole of silver halide of tetradecamethylene bis (pyridinium perchlorate) (referred to in Table IX as Q-salt). The modified emulsion was then coated and dried. The coatings, numbered a and b, respectively, in the following table were then exposed on an Eastman Ib sensitometer and developed in a conventional hydroquinone, p-methylaminophenol sulfate developer as described in Example 1, fixed, washed and dried. The following data were obtained. 7

TABLE IX Coat- Rela ing Sensitization tive Gamma Fog No. Speed a Selenium-gold 100 .91 16 b Selenium-gold plus PEG plus Q- salt 141 .88 .29

It has been further found that the speed of my seleniumgold sensitized emulsions can be further increased by including therein a thioether sensitizer of the type described in U.S. Patents 3,046,134; 3,021,215; 3,062,646; or 3,038,- 805. For example, the control emulsion of Example 9 was increased in speed from to by including therein a thioether sensitizer of the type described in U.S. Patent 3,046,132. While a 55 percent increase in speed was obtained, the fog level only rose from .05 to .15.

EXAMPLE 10 A selenium-gold-sensitized, gelatino silver bromoiodide emulsion was prepared as described in Example 1 of this application, and the emulsion was coated on a conventional cellulose acetate film'support and dried. A second sample of the same emulsion was prepared and then modified by the addition of 33 g. per mole of silver halide of a carboxyrnethyl protein of the type described in U.S. Patent 3,011,890. This sample was also coated on cellulose acetate film support and dried. The samples, numbered a and b respectively in the following table, were then exposed and processed as described in Example 7 above. The following results were obtained:

A selenium-gold-sensitized, gelatino silver bromoiodide emulsion was prepared as described in Example 1 of this application, and the emulsion was coated on a conventional cellulose acetate film support and dried. A second sample of the same emulsion was prepared and then modified by the addition of 40 g. per mole of silver halide of polyacrylamide (e.g., a polymer of the type described in U.S. application Serial No. 301,177, filed August 9, 1963). This sample was also coated on cellulose acetate film support and dried. The samples, numbered a and b respectively in the following table, were then exposed and processed as described in Example 1 above. The following results were obtained:

To one mole of a gelatino silver bromoiodide (94 mole percent bromide, 6 mole percent iodide) photographic emulsion was added 2 mg. potassium chloroaurate, 2 mg. sodium thiosulfate pentahydrate, 100 mg. sodium thio cyanate and 1.6 mg. N,N-dimethylselenourea. The emulsion was then digested at 60 C. to obtain optimum sensitivity. The emulsion was then divided into several portions to which were added the concentrations of the addenda listed in Table XII below. The emulsions were then coated on a film support to yield a silver coverage of 540 mg. per square foot and a gelatin coverage of 500 mg. per square foot. Samples of fresh and incubated coatings were exposed in an Eastman Ib sensitometer, developed for 5 minutes in the developer described in Example 1, fixed in hypo, washed and dried to yield the for a specified period at C., as indicated in Table following results: XIII. After adding the compounds listed below, the

TABLE XII Fresh One Week Inc.

120 F50% RH. Feature Addenda (gJAg mole) Rel. v Fog Rel. 'y Fog Speed Speed Control 100 2 .64 0.16 120 1 .42 1 .94 Control plus Compound 11 (10.0) 100 2.64 0.12 2.20 0.98 Control plus Compound II (20.0) 105 2.64 0.12 2.42 0.70 Control plus Compound III (20.0) 91 2.66 0.12 69 1.93 1.30 Control plus Compound IV (10.0) 100 2.70 0.16 120 1.86 1 .38 Control plus Compound I (2.0) 100 3.00 0.07 138 2.80 0.17 Control plus Compound I (2.0) plus Corupound II (10.0) 100 2.34 0.06 115 2.70 0.13 Control plus Compound I (2.0) plus Compound II (20.0) 2.86 0.06 105 2.60 0.12 Control plus Compound I (2.0) plus Compound III (10.0) 100 2.94 0.06 120 2.80 0.13 Control plus Compound I (2.0) plus Compound III (20.0) 100 2.94 0.06 105 2.50 0.11 Control plus Compound I (2.0) plus Compound IV (l0.0) 105 2.80 0.08 120 2.50 0.24 Control plus Compound I (2.0) plus Compound IV (200) 2.82 0.06 2.62 0.18

In the above table, Compound I is 4-hydroxy-6-methyl- 1,3,3a,7-tetrazaindene, Compound II is methyl-L-arabonate, Compound III is D-arabonamide and Compound IV is glucono-y-lactone. Other related hydroxy carboxylic acid derivates that can also be suitably utilized as antifoggants in the described gelatino silver bromoioemulsion samples were coated on a cellulose acetate film support at a coverage of 540 mg. silver and 500 mg. gelatin per square foot. Portions of the films were exposed in an Eastman type Ib sensitometer, developed for 5 minutes in the developer described in Example 1, fixed in hypo, washed and dried in the usual way.

1 A =triphenylphosphine.

B =B-carboxyethyl-diphenylphosphine. C =B-cyanoet hyl-diphenylphosphine. D bis-(fl-oyanoethyl)-pl1e11y1phosphine.

dide emulsion at concentrations of 20 grams per mole of silver halide, or in combination with 2 grams per mole of silver halide of 4-hydroxy-6-methyl-1,3,3a,7- tetrazaindene, include: diethyl mucate, methyl D-arabonate, ethyl D-arabonate, methyl L-arabonate tetraacetate, D-arabono y-lactone, isobutyl D-arabonate tetra acetate, methyl (tetraacetyl-D-arabonyl)glycolate, D- gluco-D-gulo-'heptano-yslactone, D gluco-D-gulo-heptonoamide, methyl D,L-glycerate, dimethyl D-tartrate, D- glucono-S-lactone, Dgluconamide, D-gluco-D-gulo-heptonic acid hexaacetate monohydrate, D-galactonic acid pentaacetate, D-arabono-y-lactone, D-galactonamide, D- lyxono-y-lactone, D-mannonamide, and the like. Such hydroxy carboxylic acid derivatives can be utilized in a wide range of antifoggant concentrations, although concentrations of about 5 to 100 grams per mole of silver halide are generally utilized.

EXAMPLE 13 A medium-grain gelatino silver bromoiodide emulsion containing about 3 mole percent iodide and about 97 mole percent bromide was sensitized by adding 2.75 mg. potassium chloroaurate, 100 mg. sodium thiocyanate and 0.8 mg. N,N-dimethylselenourea, and thereafter heating Such organic tertiary phosphine antifoggants can be utilized in a wide range of antifoggant concentrations althrough about .5 to 25 grams per mole of silver halide are more generally utilized.

EXAMPLE 14 A moderately coarse-grain, gelatino thallous bromoiodide emulsion containing 13 mole percent iodide and 87 mole percent bromide was chemically sensitized by adding, per mole of thallous halide, 10 mg. potassium chloroaurate and 40 mg. DL-cystine and thereafter heating for 10 minutes at 40 C., then cooling to 35 C. A second portion was chemically sensitized with 10 mg. potassium chloroaurate and 40 mg. seleno-DL-cystine and heated in the same manner. The chemically sensitized emulsion was coated on a cellulose acetate support at a coverage of 306 mg. thallium and 450 mg. gelatin per square foot. A sample of each coating was hardened by bathing 5 minutes in a 3 percent solution of potassium chrome alum, washed, and dried. Each sample was exposed through a step tablet for 5 minutes with a 500- watt photoflood lamp at a distance of 9 inches. Each exposed sample was processed at 68 F. by bathing 5 minutes in a 10 percent silver nitrate Solution, Washing 21 1 minute in distilled water, bathing minutes in a 2 percent potassium bromide solution, washing 1 minute in distilled Water, developing 4 minutes in the developer described below, followed by the usual fixing in hypo,

22 EXAMPLE 15 A series of coarse-grain gelatino silver bromoiodide emulsions sensitized with gold chloride and N,N-dimethylselenourea was prepared as described in Example 1.

washing and drymg' The develop utilized had the 5 Various salts of Group 11 elements were incorporated following formula: into the emulsions as antifoggants. The emulsions were Water about F C) 5000 coated on cellulose acetate film sup-ports at coverages N methyl p aminophenol Sulfate 2'0 of 459 mg. of silver and 1040 mg. of gelatin per square Sodium sulfite desiccated 900 foot. Each coating was exposed on an Eastman Ib Hydroquinone sensitometer, before and after an incubation, and then Sodium carbonate, monohydrated 525 developed for 3 minutes in the developer described below, Potassium bromide 50 and thereafter fixed in hypo, Washed and dried in the Water to make one mgr. usual manner. The developer had the following composinon. Table XIV below summarizes the results of the exposure 10 Grams and development of the prepared coatings. N-methyl-p-aminophenol sulfate 2.2 Sodium sulfite, desiccated 72.0 TABLE XIV Hydroquinone 8.8 V Sodium carbonate, anhydrous 130.0 Chemical sensitizeis Relat e Speed 1 F09 20 Potassium bromide 40 Water to make one liter.

KAuCli plus cystine 100 0.15

KAuCl plus seleu0-cystine..-. 1.000 0.09 Table XV below summarizes the results of the exposure and development of the prepared coatings.

TABLE XV Fresh 1 Wk. Inc. at 2 Wk. Inc. at

120 F. 50% R.H. 120 F. 50% R.H. Feature Addenda (gJAg mole) Rel. 'y Fog Rel. 7 Fog Rel. 1 Fog Speed Speed Speed Control 100 1. 96 .12 0. 90 1, 0+ Control plus calcium nitrate g.) 105 2.02 12 138 l 40 0.32 166 1. 32 0.40 Control plus zinc nitrate g.) 83 2. 12 10 91 1. 46 0.22 110 1. 60 0.20

Control 100 1.77 .08 105 1 20 0. 48 0.72 Control plus strontium nitrate g.) 95 1.91 10 83 1. 51 0.32 83 1. 17 0. 48

Control 100 1.94 .10 1.0 1.0 Control plus magnesium sulfate (30 g.)- 105 1. 83 22 105 1.60 0.30 110 1. 0.36 Control plus cadmium sulfate (40 g.) 73 2. 08 06 53 1. 41 0.24 1. 40 0.18 Control plus zinc sulfate (30 g.) 80 2. 06 12 69 1. 70 0. 14 63 1. 59 0. 14

Control 100 1. 96 12 0.90 1. 0 Control plus zinc sulfate (20 g.) 91 2. 10 12 91 1. 67 0. 14 73 1. 75 0. 26

Control 1. 77 08 1. 20 0. 48 0. 72 Control plus 3-hydroxy-1-propane sulionic acid. Magnesium sulfate (40 g.) 91 1. 94 06 1. 46 0.22 1. 36 0. 29

Control 100 1.96 .10 1 0 1 0 Control plus 3-hydroxy-1-propane sulionic acid. Calcium salt (40 g.) 105 1.86 08 174 1. 84 U. 24 115 1.65 0.38

Control 100 1.94 .10 1 0 1 0 Control plus 3-hydroxy-1-propa ulionio acid. Barium salt (30 g.) 100 1. 90 12 105 1.63 0. 32 105 1. 25 0.50 Control plus 3-hydroxy-1-propan fouic acid. Strontium salt (40 g.) 115 2. 08 10 100 1. 71 0.20 83 1. 55 0.42

Control 100 1. 51 08 0. 60 1. 0 Control plus cadmium nitrate (30 g.)- 91 1. 73 07 105 0. 98 0.38 105 1. 16 0.26

Control 100 1. 70 10 105 1. 20 0.40 0.90 Control plus barium nitrate (20 g.) 105 1. 65 10 105 1. 40 0. 16 112 1. 26 0.24

Control 100 1. 43 08 115 1. 00 0. 34 0.62 Control plus magnesium nitrate (20 g.) 100 1. 58 06 105 1. 23 0.14 97 1. 16 0. 15

The preparation of thallous bromide and thallous bromoiodide emulsions is described in papers by I. A. Thom, Sci. et Ind. Phot. (2), 18, 193-204 (1946); N. Ritchie and J. A. Thom, Trans. Far. Soc. 42, 418 (1946); and E. Brauer and H. J. Wehran, Phot. Korr. 93, 67 (1957). Chemical sensitizations of thallous bromoiodide emulsions by rhodium chloride, gold chloride, sodium thiosulfate, cystine, and active gelatins (alone or in combination) are described in papers by E. Brauer, Phot. Korr. 94, 35 (1958), E. Brauer, Phot. Korr., 93, 67 (1957), and E. Brauer, Sci. et Ind. Phot. (2), 29, 161 (1958).

' A wide variety of other water-soluble salts of Group 11 elements with atomic weights of about 10 to 200 can be utilized. Generally about 5 to 75 grams, and preferably about 15 to 50 grams, of such water-soluble salts per mole of silver halide are utilized as antifoggants.

EXAMPLE 16 23 415,596 filed December 3, 1964. The resulting photographic element is immersed for five minutes at 68 F. in the following solution:

Mg. Potassium chloroaurate 4.00 N,N-Dimethylselenourea 0.25

Water to make 200 ml.

(pAg adjusted to 8.5 with aqueous potassium bromide.) The resulting treated photographic element is then allowed to air dry in the dark at 68 F. The dried photographic element and a control element not immersed in the abovedescribed solution are then exposed to roomlight for seconds through a neutral density stepwedge and developed for 10 seconds in Kodak D-72 developing solution which is modified by the addition of 2.5 grams of sodium thiosulfate per liter, fixed in hypo, washed and dried in the usual manner. Comparison of the exposed and processed photographic elements indicates that the photographic element immersed in the solution containing the gold and selenium salts had substantially greater sensitivity to roomlight than does the photographic element not treated with such salt solution.

EXAMPLE 17 A series of coarse-grain gelatino silver bromoiodide emulsions sensitized with gold chloride and N-N-dimethylselenourea were prepared and coated as described in Example 1. Various antifoggants and combinations of antifoggants as described below in Table XVII were incorporated into portions of the silver halide emulsion before coating, exposed on an Eastman Ib sensitometer, both before and after incubation for 2 weeks at 120 F. and 50% relative humidity, developed as described in Example 1, fixed in hypo, washed and dried in the usual manner. The incubated coatings containing the antifoggant addenda showed substantially less fog than control coatings containing no antifoggant addenda. Table XVII below tabulates the various antifoggant addenda utilized and typical concentrations utilized in terms of grams per mole of silver halide.

TABLE XVII 24 (l) Ammonium chloropalladate .051

4 acetyl 3 methylthio 1,2,4 thiadiazoline- S-thione .03 (m) Ammonium chloropalladate .051

4-benzoyl-3 methylthio 1,2,4 thiacliazoline- S-thione .06 (n) Ammonium chloropalladate .051

4-hydroxymethyl-4-thiazoline-2-thione .05 (o) Ammonium chloropalladate .051

N-(2 chlorobenzyl) 2 benzothiazolesulfonamide 3 (p) Ammonium chloropalladate .051

3,4-dihydroxybenzaldoxime 3 (q) Ammonium chloropalladate .051

4-azidobenzolaniline 1 (r) Ammonium chloropalladate .034

Urazole 6 EXAMPLE 18 A coarse-grain gelatino bromoiodide emulsion (98 mole percent bromide and 2 mole percent iodide) containing 40 g. gelatin per silver mole, to which was added mg. potassium thiocyanate, 0.45 mg. dimethyl selenourea and 1.78 mg. aurous sulfide per silver mole, was split into portions. Gelatin or synthetic polymer were added as indicated in Table XVIII below and the emulsion was after-ripened by heating as indicated in the table. Further gelatin was added as indicated and the emulsions were coated at 452 mg. silver per square foot on a cellulose acetate film support. Samples were exposed in an Eastman Ib sensitometer, processed for 3 minutes in the developer described in Example 15, fixed in hypo, washed and dried in the usual manner. The results are Feature addenda: Concentrations summarized in the table. Amounts of vehicle are ex- (a) Ammonium chloropalladate .085 pressed as grams per mole of silver.

TABLE XVIII Alter-Ripening Alter-R penmg Coating, Rel.

Vehicle g. Vehicle Speed 7 Fog Time Temp., min. O.

40 g. gelatin 17 65 140 Gelatin--- 100 1.78 .10 140 g. gelatin 25 65 140 do. 107 1.90 .07 40g.gelatm 35 77.5 do 155 1.75 .11 100 g. Polymer 1 100 Polymer 1 The polymer is a copolymer consisting of 90 weight percent butyl acrylate, 10 weight percent acrylic acid.

(b) Copoly(ethylene-maleamic acid) (c) 5-t-octylsalicyclic acid (d) Ethyl-y-bromobutyrimidate I-ICl (e) Ethyl-2-furoylimidate HCl (f) 5-(3,4-dimethoxyphenyl)tetrazole (g) Di-p-tolylthiosulfinate (h) Urazole (i) e-Bromocaproamide (j) Ammonium chloropalladate in .rs soimuno-hmc.

S-t-Octylsalicyclic acid 6 (k) Ammonium chloropalladate .051

e-Bromocaproamide EXAMPLE 19 To a fine-grain gelatino silver chlorobromide emulsion containing 60 mole percent bromide and 40 mole percent chloride was added 4.4 mg. potassium chloroaurate, 50 mg. sodium thiocyanate, 2.2 mg. N,N-dimethylselenourea, and 2 mg. sodium thiosulfate. After adding the compounds listed in Table XIX below, the emusion was coated on a cellulose acetate film support at a coverage of 137 mg. silver and 202 mg. gelatin per square foot. Samples of the films were exposed in an Eastman type Ib sensitometer, both before and after an incubation period, processed for 8 minutes in the developer described in Exam- 3 pic 14, fixed in hypo, washed and dried in the usual 2o manner. The results are summarized in the following table.

TABLE XIX Fresh 1 Wk Inc., 120 1. Mg./Ag Compound mole Rel. 'y Fog Rel 7 Fog Speed Speed None (control) 100 1.90 0.10 91 0.78 A 500 91 1.88 0.06 -120 1.75 0.27 94 1.30 0.10 110 1.00 0.31 100 1.00 0.10 87 1.58 0.47 94 2.08 0.07 91 1.63 0.2 1

The compounds of Table XIX are identified as follows:

A: l- 3-acetan1idophenyl -5 -mercaptotetrazole B: 1-(3,5-dicar-boxyphenyl -5-mercaptotetrazole C l- O-carbomethoxyphenyl) -5 -mercaptotetrazole The invention has been described in detail with particular reference to preferred embodimentsthereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. In a photographic system capable of being sensitized with a noble metal, the improvement which comprises increasing the sensitivity of said system with a noble metal and labile selenium.

2. In a photographic system capable of being sentitized with a noble metal, the improvement which comprises increasing the sensitivity of said system with gold and labile selenium.

3. In a gold sensitized photographic silver halide system, the improvement which comprises increasing the sensitivity of said system with labile selenium.

4. A photographic silver halide system as described in claim 3 wherein the silver halide is substantially free of dismrsing agent.

5. A photographic silver halide system as described in claim 3 wherein the silver halide is dispersed in a hydrophilic colloid.

6. A photographic silver halide emulsion sensitized with at least two difierent sensitizers, one of said sensitizers being a noble metal sensitizer and the other of said sensitizers being a labile selenium sensitizer.

7. A photographic silver halide emulsion sensitized with at least two different sensitizers, one of said sensitizers being a gold salt and the other being a labile selenium sensitizer.

8. A photographic silver halide emulsion sensitized with a gold salt and an organic selenium compound containing divalent selenium doubly bonded to a carbon atom of said compound through a covalent linkage.

9. A photographic silver halide emulsion sensitized with a gold salt and colloidal selenium.

10. A photographic silver halide emulsion sensitized with a gold salt and a selenourea.

11. A photographic silver halide emulsion sensitized with a gold salt and selenoacetamide.

12. A photographic silver halide emulsion containing a color'forming coupler, a gold salt and labile selenium sensitizer.

13. A photographic gelatino silver halide emulsion sensitized with a gold salt and N,N-dimethylselenourea.

14. A photographic gelatino silver halide emulsion sensitized with a gold salt and diethylselenourea.

15. A photographic gelatino silver halide emulsion sensitized with a gold salt and selenourea.

16. A photographic silver halide emulsion sensitized with a gold salt and a labile selenium sensitizer, said silver halide emulsion containing in addition a watersoluble thiocyanate compound.

17. A photographic silver halide emulsion, as defined 26 in claim 16 wherein said emulsion contains a dispersion of a color forming coupler compound.

18. A photographic silver halide emulsion sensitized with a gold salt and a labile selenium sensitizer, said silver halide emulsion containing in addition a polyethylene glycol sensitizer.

19. A photographic silver halide emulsion sensitized with a gold salt and a labile selenium sensitizer, said silver halide emulsion containing in addition a quaternary ammonium salt sensitizer.

20. A photographic silver halide emulsion sensitized with a gold salt and labile selenium sensitizer, said silver halide emulsion containing a carboxymethyl protein.

21-. A photographic silver halide emulsion sensitized with a gold salt and a labile selenium sensitizer, said silver halide emulsion containing hydrophilic polyacrylamide.

22. A photographic silver halide emulsion sensitized with a gold salt and labile selenium sensitizer, said silver halide emulsion containing a hydrophilic acrylate'acrylic acid copolymer.

23. A photographic silver halide emulsion sensitized with a nobel metal sensitizer and a labile selenium sensitizer, said emulsion containing an antifoggant amount of a hydroxy carboxylic acid derivative antifoggant having a formula selected from the group consisting of 0 H i 1 (CHM)... O and ((EHZ.

H A l lo X wherein:

(1) M and Z are each selected from the group consisting of a hydroxy radical and an acyloxy radical having the formula 0 H OC=R wherein R is selected from the group consisting of an alkyl radical and an aryl radical;

(2) X is selected from the group consisting of a hydrogen atom, a carbinol radical, a radical having the formula II CH2OCR7 wherein R is selected from the group consisting of an alkyl radical and an aryl radical;

(3) Y is selected from the group consisting of a carboxy radical, a carbamyl radical and a radical having the formula i -COR wherein R is an alkyl radical;

(4) A is selected from the group consisting of a carbinol radical, a carbamyl radical, a carboxy radical, a radical having the formula wherein R is an alkyl radical and a radical having the formula 0 OHzO C R whereni R is selected from the group consisting of an alkyl radical and an aryl radical;

(5) m is an integer of 2 to 3;

(6) n is an integer of 1 to 5; and

(7) 0 is an integer of 0 to 2;

0 (II-OR (CHOH)q CHzOH wherein R is an alkyl radical having 1 to 2 carbon atoms and q is an integer of 1 to 5.

25. A photographic silver halide emulsion sensitized with a nobel metal sensitizer and a labile selenium sensitizer, said emulsion containing an antifoggant amount of a l-phenyl-5-mercaptotetrazole antifoggant.

26. A photographic silver halide emulsion sensitized with a nobel metal sensitizer and a labile selenium sensitizer, said emulsion containing an antifoggant amount of an organic tertiary phosphine antifoggant.

27. A photographic silver halide emulsion sensitized with a nobel metal sensitizer and a labile selenium sensitizer, said emulsion containing an antifoggant amount of an antifoggant selected from the group consisting of a water-soluble salt of magnesium, calcium, strontium, barium, zinc and cadmium.

28. A photographic silver halide emulsion sensitized with a nobel metal sensitizer and a labile selenium sensitizer, said emulsion containing an antifoggant amount of an azaindene antifoggant.

References Cited by the Examiner UNITED STATES PATENTS 1,574,944 10/1926 Sheppard 96--107 3,128,184 4/1964 Lowe et al 96108 3,144,336 7/1964 Herz 96-108 NORMAN G. TORCHIN, Primary Examiner.

J. RAUBITSCHEK, Assistant Examiner. 

1. IN A PHOTOGRAPHIC SYSTEM CAPABLE OF BEING SENSITIZED WITH A NOBLE METAL, THE IMPROVEMENT WHICH COMPRISES INCREASING THE SENSITIVITY OF SAID SYSTEM WITH A NOBLE METAL AND LABILE SELENIUM. 